The present invention relates to an image-receiver (e.g., a camera control system capable of controlling a camera angle) of a system comprising an image-transmitter for transmitting camera images captured by a plurality of cameras whose angles can be controlled, and the image-receiver for displaying the thus-transmitted camera images.
Recent advances made in network technology has brought out a system which transmits over a network an image captured by a camera and plays back the image at the receiving end (hereinafter often called an “image-receiving end”). Of such systems, many systems enable the image-receiving end which receives and plays back an image to control a turn table on which is mounted a camera connected to the transmitting end (hereinafter often called an “image-transmitting end”).
Japanese Patent Unexamined Publication 7-123390/(1995) describes a camera control system which enables an image-receiving end to control a camera connected to an image-transmitting end. The image-receiving end is equipped with a monitor screen having a plurality of windows for indicating a plurality of camera images (also called “camera image windows”), a camera selection button, and a camera control panel. By pressing the camera selection button while viewing images on the camera image windows, an operator selects a camera which he desires to control. The operator then presses a control button provided in the camera control panel, to thereby transmit a control command to the image-transmitting end and enable control of operation of the camera connected to the image-transmitting end.
The operation of the camera control system will now be described briefly by reference to FIG. 27.
The camera control system comprises cameras 2701 for capturing images; image transmitters 2710 for transmitting the images captured by the cameras 2701; an image receiver 2720; a display 2704 for displaying images; and an input device 2705 for entering a command which enables the image receiver 2720 to control the camera 2701 connected to the selected image transmitter 2710.
Each of the image transmitters 2710 comprises an image data import section 2711 for importing an image captured by the corresponding camera 2701; an image data transmission section 2712 for transmitting image data to the image receiver 2720; a control command receiving section 2713 for receiving a camera control command transmitted from the image receiver 2720; and a control command transmission section 2714 for transmitting the camera control command to the camera 2701.
The video receiver 2720 comprises an image data receiving section 2721 for receiving a plurality of images transmitted from the image transmitters 2710; an, image data playback section 2722 for displaying the plurality of image data sets on the display 2704; a command load section 2723 for loading a camera control command entered by way of the input device 2705; and a control command transmission section 2724 for transmitting, to the image transmitters 2710, the camera control command loaded by way of the command load section 2723.
Next will be described the flow of operation from when each of the cameras 2701 captures an image until the display 2704 displays the thus-captured images.
The image captured by the camera 2701 is imported into the image data import section 2711, and the image data import section 2711 delivers to the image data transmission section 2712 data pertaining to the thus-imported image. The image data transmission section 2712 transmits the image data to the image data receiving section 2721 of the image receiver 2720. The image data receiving section 2721 receives a plurality of image data sets from the plurality of image data transmission sections 2712 and delivers the thus-received image data sets the image data playback section 2722. The image data playback section 2722 displays a plurality of images on the display 2704.
There will be now described the flow of operation through which the image receiver 2720 controls the cameras 2701 connected to the plurality of image transmitters 2710. FIG. 28 shows an example camera control panel for controlling the cameras 2701 and example images captured thereby to be displayed on the display 2705. A display screen 2800 comprises image display areas 2801, 2802 and 2803 for displaying images captured by the plurality of cameras 2701; a camera control panel display area 2801; and a control camera selection display area 2830. The camera control panel display area 2810 comprises an UP button 2811, a DOWN button 2812, a LEFT button 2813, and a RIGHT button 2814 for panning the camera 2701 vertically or hoizontally; an IN button 2817 and an OUT button 2818 for causing the camera 2701 to zoom in and out; and a focusing button 2819 and defocusing button 2820. The control camera selection button 2830 comprises camera selection buttons 2831, 2832 and 2833.
By way of the input device 2705 shown in FIG. 27, the operator selects a camera he desires to control, by means of pressing any one of the camera selection buttons 2831, 2832, and 2833 and pressing any of the buttons 2811 through 2820. The command load section 2723 loads a control command assigned to the camera selected by means of the camera selection button and delivers the thus-loaded control command to the control command transmission section 2724. The control command transmission section 2724 transmits the control command to the control command receiving section 2713 of the image transmitter 2710 corresponding to the camera selection button selected from the camera selection buttons 2831, 2832, and 2833. Upon receipt of the control command, the control command receiving section 2713 delivers the thus-received control command to the corresponding control command transmission section 2714. The control command transmission section 2714 delivers the control command to the corresponding camera 2701, whereupon the camera 2701 performs the operation instructed by way of the input device 2705.
The camera control system of background art encounters the following drawbacks:                1) In a case where the camera control system is equipped with a plurality of cameras, the operator must designate a camera to be controlled. Even after designation of a camera, there may be a chance of another camera being able to capture a desired image with rotation less than that which would be required by the designated camera. Selection of a camera capable of capturing a desired scene most quickly is left to the operator's judgment. However, in many cases, optimal judgement is not rendered by the operator.        
2) Even in a case where the operator designates and controls a camera, an impediment may block the camera from capturing a desired image.
3) Even in a case where the operator designates and controls a camera, another camera may be able to more quickly attain focus on a desired location through rotation than can the designated camera. The operator is uncertain of which camera that can shoot a desired location in the least amount of time.
4) Even in a case where the operator designates and controls a camera, to thereby train the camera on a desired location, the user is uncertain as to whether or not the location is viewable from the direction from which the operator desires to shoot.
5) Even in a case where the operator designates and controls a camera, another camera may be able to more quickly zoom in a desired range through rotation than can the designated camera. The operator is uncertain of which camera can zoom into a desired range in the least amount of time.
6) In a case where the operator designates and controls a camera, even if an image captured by a camera under control is subjected to rotation, the operator encounters difficulty in ascertaining the image which is currently being controlled, since all the images captured by the cameras are in motion.
7) When desiring to view details of a certain location and its surroundings simultaneously, the operator must control two or more cameras independently through use of control commands, thus consuming time.